1. Field of the Invention
The present invention relates to sewage grinder pumps and, more particularly, to an improved horizontal lower collection tank assemblage for a grinder pump station that can accommodate one or more grinder pump units mounted to the inside of the single collection tank.
2. Description of the Background
Sewage grinder pump stations are well-known, as exemplified in U.S. Pat. No. 5,562,254 issued to Sleasman et al. On Oct. 8, 1996 (which specification is incorporated by reference herein).
FIG. 1 is a perspective drawing from the '254 patent illustrating the grinder pump station 10, and FIG. 2 is a cross-section drawing from the '254 patent illustrating lower tank portion 16 formed by a cylindrical non-corrugated inner wall 52 and a corrugated outer wall 54.
FIG. 3 illustrates how the prior art grinder pump station 10 of FIGS. 1 and 2 is installed in the ground.
As seen throughout FIGS. 1-3 and as fully described in the '254 patent, this grinder pump station 10 is positioned substantially vertically in the ground. Grinder pump station 10 includes a lid assembly 22, an upper tank portion 14, a transition section 18, a lower tank portion 16, and a base 32. The outer side walls of upper tank portion 14 and lower tank portion 16 are corrugated, while the outer side wall 17 of transition section 18 is smooth. Extending through side wall 17 of transition section 18 is an inlet opening 20 through which sewage enters grinder pump station 10, and a discharge opening 19, through which processed sewage exits grinder pump station 10. Attached to this upper tank portion 14 is a lid assembly 22. Lid assembly 22 includes the electrical and ventilation interfaces of the grinder pump station, as more fully described hereinafter, and an access hatch 24 for allowing interior access. A base 32 is secured to the lower portion 16 of grinder pump station 10. Mounted within grinder pump station 10 is a grinder pump unit 34. Grinder pump unit 34 includes a grinder head 36 for pulverizing sewage. A grinder pump 39 is secured to grinder head 36 for pumping ground sewage through grinder pump station 10. Grinder pump 38 includes a discharge housing 40, which is joined to a discharge outlet pipe 42. A sealed control housing 44 houses the controls for grinder pump 34, and underneath housing 44, a motor housing casting 47 houses an electric motor (not shown) for powering both grinder pump 38 and grinder head 36. Grinder pump unit 34 employs one or more sensing tubes 46 to sense pressure variations by measuring increases in the level of sewage collected in grinder pump station 10. Upon the attainment of a predetermined sewage level, the motor within motor housing casting 47 is energized. The sewage collected in grinder pump station 10 is then be ground by grinder head 36 and is pumped by grinder pump 38 from discharge housing 41 to discharge outlet pipe 42. From discharge outlet pipe 42, the processed sewage travels to a remote location, e.g., to a pressure sewage main and ultimately to a sewage treatment plant. The entire above-described grinder pump unit is commercially available as the Model 2000 Series from Environment One Corp., Schenectady, N.Y.
With particular reference to the tank portions 14 and 16 of grinder pump station 10, it can be seen that the upper tank portion 14 and lower tank portion 16 are identical in every respect apart from their relative height. Both upper tank portion 14 and lower tank portion 16 have a substantially cylindrical non-corrugated inner wall 52 secured to a substantially cylindrical corrugated outer wall 54. The corrugations of the outer wall 54 form a series of alternating crests 56, ridges and troughs 58. Each trough 58 of corrugated wall 54 is secured, during the manufacturing process, to inner wall 52. An extrusion method of manufacture can be employed to form the corrugated configuration, wherein the cylindrical corrugated outer wall 54 and cylindrical inner wall 52 integrally form double walled upper tank portion 14 and lower tank portion 16.
A transition section 18 separates the upper tank 14 from lower tank 16. Transition section 18 is substantially cylindrical in shape, and has a non-corrugated outer wall to facilitate the formation of one or more inlet openings 20 and discharge openings 19 through its sides, and has an enlarged axial opening extending therein. Transition section 18 includes structure for positioning and aligning grinder pump unit 34 in grinder pump station 10. The inner diameter of transition section .backslash.18 is defined by the axial opening, and the outer diameter is defined by outer side wall 17. An internal conical wall 118 forms the upper reservoir portion of transition section 18, while conical wall 118 flows inward from the outer diameter to a proximity near the inner diameter of the transition section. The conical shape provides structural stiffness for transition section 18 and facilitates the insertion of grinder pump unit 34 into the axial opening or transition section 18. The grinder pump stations, lower tank portions, and transition sections as described above and as illustrated in the '254 patent are commercially available from Environment One Corp., Schenectady, N.Y.
It is noteworthy that the above-described design is limited to the illustrated vertical/coaxial configuration of the upper and lower tank portions 14 and 16 of grinder pump station 10. This configuration ostensibly allows for easy field height adjustability, in small increments. However, the vertical configuration can only accommodate a single grinder pump unit, and the overall storage volume is very limited. Moreover, FIG. 3 shows the use of concrete reinforcement 143 for the submerged tank. Concrete reinforcement 143 is necessary to support the vertical and coaxial configuration of the upper and lower tank portions 14 and 16. A concrete truck must somehow gain access to the site, and this greatly increases the cost of manufacturing and installation.